A prior example of the present invention includes Japanese Patent Application Laid-Open No. 10-113725 (1998) (prior example 1) and Japanese Patent Application Laid-Open No. 2000-288656 (prior example 2).
In the prior example 1 (Japanese Patent Application Laid-Open No. 10-113725 (1998)), a punch body having a punch blade portion on its lower end is provided in a cylindrical punch guide so as to be movable up and down, an oscillation locking piece having a latch portion being freely engaged with an engagement groove formed on an outer peripheral surface of a stripper plate on its lower end is provided on a lower end of the punch guide so as to freely oscillate to an inside-outside direction and be energized to an outside direction, and a turning ring, which has a locking piece pressuring portion for pressuring the oscillation locking piece to an inside direction so that the latch portion of the oscillation locking piece is engaged with the engagement groove of the stripper plate, is turnably provided to the lower end of the punch guide.
In the prior example 1, although the stripper plate can be attached to and detached from the lower end of the punch guide comparatively easily, the oscillation locking piece is made of a plate spring and it is occasionally broken at the attachment portion to the punch guide.
In addition, since the configuration is such that the turning ring is energized to a turning direction by a coil spring so that the latch portion of the oscillation locking piece is maintained to be engaged with the engagement groove of the stripper plate, a further improvement is desired in relation to that the turning ring occasionally turns against an energizing force of the coil spring due to vibration or the like at the time of a punching workpiece.
On the other hand, in the prior example 2 (Japanese Patent Application Laid-Open No. 2000-288656), in a configuration that a punch body having a punch blade portion on its lower end is provided into a cylindrical punch guide so as to be movable up and down, and a disc-shaped stripper plate encircling the punch blade portion is detachably provided to a lower end of the punch guide, a stopper ring is elastically mounted between a ring member fixed to an upper end of a punch driver fitted to an upper portion of the punch guide so as to be movable only up and down and an upper surface of the punch guide, a punch head member having a punch head on its upper end is fitted into the punch driver rotatively, and an external thread portion provided to an upper portion of the punch body is screwed into an internal thread portion provided to the punch head member so that an up-down position is adjustable.
In the above configuration, although the height adjustment after repolishing of the punch blade portion can be made easily, it is difficult to grasp a repolishing quantity of the punch blade portion, and the internal thread portion and the external thread portion are occasionally screwed firmly at the time of assembly after the repolishing. Thus, a further improvement is desired.
The present invention is devised in order to solve the above problems, and its first object is to provide a die device in which the height adjustment after the repolishing of the punch blade portion is easy.
A second object of the present invention is to provide a die device which is capable of attaching/detaching and fixing the stripper plate easily and securely.